Linux: Mac4Lin, a package of skins, wallpapers, icons and interface refinements that brings a completist Mac look to Linux with an automated installation, has reached the 1.0 stage with an impressive array of features.
Besides basic theming changes to your desktop covering login windows, window look and feel, a modified app launcher dock, and more, Mac4Lin plugs into and plays nice with a lot of third-party apps. Thunderbird, Rhythmbox, Songbird, Pidgin, Firefox 3 and others are supported and receive theme integrations, while a customised Cairo or AWN dock are rolled into your system during the installation.
There are, obviously, areas where the Linux desktop can't replicate the Mac. Still, if you like the Cupertino look for your system, Mac4Lin is an easy way to get there, without an afternoon-consuming step-by-step process.
Mac4Lin 1.0 is a free download for Linux systems. Hit the link below for a list of features, standing bugs, and screenshots.